562 THE SAKIS CHAP. 



traversed by the Eio Negro ; the Bald-headed Ouakari appears 

 to be confined to the triangle formed by the union of the 

 Amazon with another affluent, the Japura ; and the Eed Ouakari 

 to the forests on the north bank of the Amazon opposite Olivenc,a, 

 and lying between the main stream and the Eiver Ic,a. Each of 

 them evidently takes the place of the others in its particular 

 district. Of this peculiar kind of distribution few instances are 

 known amongst mammals, but many somewhat similar cases have 

 been observed in birds, reptiles, and insects." 



The genus Pithecia, the Sakis, consists of five species with 

 long bushy tails, which are non-prehensile. They are bearded 

 and have a thumb. Like the last genus, Pithecia does not 

 extend into Central America. The incisors project forwards, and 

 the lower jaw is deep, though the howling apparatus of Mycetes 

 is wanting. The thin, closely-set, and projecting incisors are very 

 suggestive of those of the Lemurs. Brachyurus is much like 

 Pithecia in this respect, and both differ markedly from such a 

 genus as Cebus, where the lower incisors are vertical. An 

 anatomical peculiarity of Pithecia is the breadth of the ribs. 

 P. satanas is perhaps the best-known species, but all five have 

 been exhibited at the Zoological Society's Gardens. As its 

 name suggests, P. satanas is entirely black ; it shows a curious 

 point of difference from P. cheiropotes in its way of drinking. 

 The latter species, as its name denotes, uses its hand to drink, 

 while P. satanas puts its mouth to the water. P. albinasa is 

 black with a red patch on the nose, within which again is a 

 small white patch. 



GROUP II. CATARRHINA. 



The Catarrhine Apes are divisible into three or perhaps only 

 two families, the Cercopithecidae and the Simiidae, to which 

 must be added the Hominidae. The Simiidae are sometimes 

 spoken of as the Anthropoid Apes. 



Pam. 1. Cercopithecidae. Of the Cercopithecidae there are 

 eight genera (perhaps nine) to be recognised, which may be dis- 

 tributed into two sub-families. The first of these two sub-families, 

 that of the Cercopithecinae, has the following characters : There 

 are cheek pouches in which the animals store food temporarily. 



